It is normally considered desirable for the sake of appearance or security to provide a cover that can move into position above the cargo space of a motor vehicle, for instance over the wayback of a station wagon or utility vehicle, to conceal and confine any objects therein. Such a cover comprises at the least a winder that is positioned at an inner end of the space, normally against the seat backs defining the front wall of the space, and a cover sheet that can be wholly wound up in the winder or extended therefrom so its outer edge is at the outer end of the space, normally just short of a rear hatch or door.
In a typical powered system described in German patent document 4,016,707 the cover assembly is basically U-shaped with a pair of guide arms that flank the space and that each carry a respective entrainment element movable in and out along a respective side of the space. The outer edge of the cover sheet has a rod with ends fixed to the entrainment elements and the guides are provided with flexible drive elements that extend back to a common motor mounted in the base of the unit that joins the inner ends of the two guides.
Such an arrangement has several disadvantages. First of all if the rear seats are folded down or removed to increase the cargo area, the elements joining the inner ends of the guides extend across this space and greatly reduces its usability. In addition the unit cannot readily be adapted for use in different vehicles as the width and length of the cargo space can vary considerably and it is impossible to make the system variable in width and length to the same extent.
A sun roof is known from European 0,368,405 where the glass panel is moved by a pair of flanking motors interconnected by a flexible shaft. Such a system bears little resemblance to a cargo-space cover and the flexible shaft interconnecting the two separate drive motors constitutes just the same type of structure that makes the above-described cargo-space cover so disadvantageous.
Similarly German utility model 9,102,196 describes a system for operating curtains, security grates, and the like which uses a spring-loaded winder and wherein the outer edge of the sheet or grid being wound in and out has a rod whose ends are each displaced by a respective cable operated by a respective motor. The tensions in the cables are monitored and the motors are operated to keep the two tensions substantially equal so as to synchronize movement of the ends of the rod. Such a system is capable of jamming and is also hardly applicable to a cover sheet for a cargo space.